Identification and characterization of the main β-alanine uptake system in Escherichia coli
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In Escherichia coli, β-alanine is a direct precursor in the biosynthesis of pantothenic acid (vitamin B5). Although a sufficient β-alanine supply is crucial for biotechnological vitamin B5 production, nothing was known about β-alanine transport in E. coli until now. The aim of this work was the characterization of β-alanine transport by E. coli and the identification and overexpression of the corresponding carrier-encoding gene for the rational improvement of pantothenic acid-producing strains. β-Alanine uptake was found to be an active process catalyzed by the amino acid carrier CycA. The corresponding gene was cloned and overexpressed, resulting in an increase in the uptake rate, compared with the wild type. In all tested strains, this overexpression led to a strong sensitivity to β-alanine, but not to the other CycA substrates, such as l-alanine, d-alanine, and glycine. This prevented a direct application for the improvement of pantothenic acid-producing strains by an enhanced precursor supply.
KeywordsCarnosine Pantothenic Acid Pantothenate Biosynthesis Ketopantoate Amino Acid Transporter Family
This work was supported by Degussa AG (Hanau).
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